Abstract 256: Assessment of Intraventricular Mechanical Dyssynchrony and Prediction of Response to Cardiac Resynchronization Therapy: Comparison Between Tissue Doppler Imaging and Real-Time Three-Dimensional Echocardiography
Objectives: We studied
the comparability of LV mechanical dyssynchrony (LVMD) assessment by tissue Doppler imaging (TDI) and real-time three-dimensional echocardiography (RT3DE) in patients with a wide range of LV ejection fractions and different etiologies of cardiomyopathy, and
the ability of both techniques to predict response to cardiac resynchronization therapy (CRT).
Methods: A total of 90 patients and 30 healthy volunteers underwent both TDI and RT3DE. A subgroup of 27 patients underwent CRT and were evaluated before and 6 months after implantation. LVMD was measured with TDI using the standard deviation of time to peak systolic tissue velocity of 12 LV myocardial segments. With RT3DE, the standard deviation of time to minimal volume of 16 LV subvolumes was assessed. Response to CRT was defined as a reduction of ≥15% in LV end-systolic volume at 6 months.
Results: A moderate correlation (r=0.581, P<0.001) was observed between TDI and RT3DE. No significant difference in presence of LVMD by TDI and RT3DE was observed (53% versus 48%, respectively). Agreement between techniques was comparable between patients with ischemic and nonischemic cardiomyopathy. However, up to 30% nonagreement between techniques was found, depending on the severity of LV dysfunction. Of the 27 patients undergoing CRT, 63% of patients were classified as responders. All baseline characteristics were similar between responders and nonresponders, except for LVMD assessed by RT3DE, which was significantly higher in responders compared with nonresponders (10.0±2.8% vs 6.3±2.3%, P=0.001). Applying previously defined cutoff values, ROC curve analysis demonstrated a sensitivity of 59% with a specificity of 50% for TDI, and a sensitivity of 88% with a specificity of 60% for RT3DE to predict response to CRT. The optimal cutoff value for SDI by RT3DE of 6.7% yielded a sensitivity of 88% with a specificity of 70% to predict response to CRT.
Conclusions: Marked differences between techniques are found for the presence of LVMD when current cutoff values are applied, making interchangeability of these techniques uncertain. Assessment of LVMD by RT3DE might be an appropriate alternative to TDI for accurate prediction of response to CRT.